Sludge inhibiting jet fuel additives and methods for their use



United States Patent 3,361,545 SLUDGE IITlNG JET FUEL ADDITIVES ANDMETHODS FOR THEIR USE Richard L. Raymond, Wilmington, Del., and John D.Douros, Jr., West Chester, and John J. Melchiore, Wallingford, Pa.,assignors to Sun Oil Company, Philadelphia, Pa., a corporation of NewJersey N0 Drawing. Filed Jan. 15, 1962, Ser. No. 166,361 The portion ofthe term of the patent subsequent to Jan. 14, 1981, has been disclaimed.18 Claims. (Cl. 4470) This invention relates to a method of protectinghydrocarbon distillate compositions from attack by microorganisms.

More particularly this invention concerns the addition of certaindi-substituted naphthalene additives to the above hydrocarbondistillates to inhibit the growth of sludge or slime producingmicroorganisms.

These microorganisms include such classes as the bacteria,actinomycetes, algae, fungi, and yeasts.

These inhibitors are di-substituted naphthalenes in which thesubstituents pairs are selected from the group consisting of alkyl-alkylester, alkyl-formyl, alkyl-hydroxyalkyl, alkyl ester-formyl, alkylester-hydroxyalkyl, alkyl ester-alkyl ester, formyl-hydroxyalkyl,hydroxyalkyl-hydroxyalkyl, 1,8-dialkyl, 1,2-dialkyl, 1,6-dialkyl, andmixtures of 1,8-, 1,2-, and 1,6-dialkyl.

As used throughout this disclosure the alkyl and hydroxyalkyl areunderstood to be those radicals having at least 1 and no more than 6carbon atoms, branched or unbranched, joined or conjoined.

lllustrative examples of the inhibitors intended to be Within thisinvention include 1,8-dimethylnaphthoate, *l,6- diethylnaphthoate,1,2-dipropylnaphthoate, 2,6-dihydroxymethylnaphthalene,l,4-dihydroxyethylnaphthalene, 6-hydroxypropyl-Z-methylnaphthalene,Z-hydroxyethyl-S-ethylnaphthalene, 6 formyl 2 ethylnaphthoate,8-formyl-1 propylnaphthoate, 6-formyl-Z-methyInaphthalene,l-formyI-Z-ethylnaphthalene, 1-formyl-2-methylnaphthoate, 8- formyll-propylnaphthoate, 4-hydroxymethyl-1-methylnaphthoate,2-formyl-l-hydroxymethylnaphthalene, 6-formyl-l-hydroxyethylnaphthalene,1,8-dimethylnaphthalene, 1,2-dimethylnaphthalene, and l,6dimethylnaphthalene, among others.

By hydrocarbon distillates is meant those cuts of petroleum distillatescomprising mostly saturated aliphatic and cyclic hydrocarbons withlittle or no aromatic content. These include kerosene, straight rungasolines and heating oils. Particularly of interest are the kerosenetype aviation fuels known as jet fuels or more properly referred to asturbine engine fuels. By heating oils and gasoline is meant those cutsof hydrocarbon distillates used for heating purposes or as fuels for aninternal combustion machine in automobiles or aeroplanes.

The term microorganisms as used throughout this disclosure refers tothose organisms of biological origin, of microscopic or ultramicroscopic size, capable of metabolizing or feeding upon jet fuelsubstrates in the presence or absence of oxygen. These microorganismsinclude but are not limited to bacteria, fungi, yeasts, molds, algae,protozoa, and the like. Microorganisms particularly troublesome to jetfuels include among many others the following genera: Penicillium,Aspergillus, Spicaria, Helminthosporium, Pseudomonas, Aerobacter,Bacterium, Clostridium, Cladosporium, as well as certain gram-negativeDiplococcus and spirochaetes.

That certain types of microorganisms are able to utilize hydrocarbons asnutrient substrates has been known for many years but has aroused littlebut academic interest.

The reason for this lack of interest was that little hydrocarbon wasconsumed. The microorganism attack took place over long periods of timeand no perceptible change in the hydrocarbon fuels was noticed by theuser.

Recently, however, with the much wider use of turbine type aircraft,large quantities of kerosene free from even trace amounts ofcontaminants are required. There have been increasing reports that theheretofore supposedly innocuous microorganism digestion of thehydrocarbons produces sludge, slime, and solid sediment which not onlycause operational difiiculties in the aircraft but induce more rapidcorrosion of the aircraft parts, particularly the fuel tanks.

While the mechanism of this sludge and slime formation is not fullyunderstood at this time, it appears as though the sludge-likecontaminants are produced by the microorganism as a metabolic wasteproduct. Whatever be the means by which the contaminating substances areproduced, it is clear that during operational use the contaminated fuelclogs and plugs the aeroplanes fuel filters and coalescers and fouls thetank gauges to the point that they become unreliable. These malfunctionsof aircraft parts interfere with efiicient engine operation, and, it issuspected, have upon occasion caused operational turbine engine failure.

An indirect but no less costly problem caused by the sludge is theincreased corrosion of the aeroplane fuel tanks. Apparently, this comesabout by the microorganisms concentrating the small amounts of waterpresent in the fuel so that small agglomerates of Water are continuouslyheld in contact with the walls of the metal tank, instead of beingdispersed innocuously throughout the fuel.

With the recognition of the existence of the sludge problem manydifferent solutions have been suggested and tried. Some of the proposedsolutions to this problem have been dehydration and purification of thefuel, adding rust inhibitors, coating the tank sides with protectivematerials, adding bactericides or fungicides to the stored compositions,and better housekeeping procedures such as more frequent cleaning of thetanks and draining of the accumulated water. Unfortunately, all of theseapproaches appreciably raise the cost of the fuel and none has proved tobe truly effective. Turbine engine fuel is already remarkably free fromwater and solid contaminants. For example, most commercialspecifications call for less than 2 mg. of solid particles per gallonand less than ppm. of water. To reduce these trace impurities further orto dehydrate the fuel more completely would be prohibitively expensiveand would undoubtedly require better storage facilities than presentlyexist to maintain the fuels at their high level of purity. The use ofbacteriostatic or fungistatic additives such as organic boron compoundis promising, but up to now, none of the recommended compounds hasproved to be completely satisfactory in so far as their activity or costof application is concerned. For example, a recent report on the problemby the Gulf Research and Development Company (Development of theMicrobiological Sludge Inhibitors) by Churchill and Leathen reveals thatall of the recommended materials required concentrations of at least 500ppm. to function effectively, and the majority required MOO-20,000 ppm.Furthermore, the cost of some of these inhibitors substantiallyincreases the cost of the fuel. Another failing of many of theseinhibitors is their exceedingly narrow spectrum of activity. Few if anyof the recommended biocides would be effective against many of the 184microorganisms disclosed (in the above report) to have been isolatedfrom contaminated fuel samples. Thus, applicants discovery that thepresence of certain di-substituted naphthalenes in small concentrationsinhibit the growth of the noxious microorganisms is a truly significantfinding, advantageous in several respects. For example, these inhibitorcompositions are soluble in the fuel phase, unlike many conventionalbiocides which are derived from salts or contain heavy metals. Thusthese inhibitors are suitable for operational turbine engine use.However, because of the extremely low concentrations required forinhibition, these inhibitors will not only protect the fuel compositionbut will also disperse in the interface between the fuel and waterphases to keep this potentially favorable growth environment free frommicroorganisms.

Another advantage of the microorganism growth inhibitors of thisinvention is their low cost and ease of preparation. These inhibitorsare well known compounds Whose preparation and properties are presentedamong other places in Chemical Abstracts and in the exhaustive review byDonaldson, entitled The Chemistry and Technology of NaphthaleneCompounds, published by Edward Arnold, Ltd, 1958. Furthermore,applicants inhibitors have a broad spectrum of activity against avariety of sludge-forming yeasts, fungi, and bacteria, including but notlimited to the following genera: Aspergillus, Alternaria, Rhizopus,Fusarium, Proteus, Pseudomonas, Salmonella, Staphylococcus, Escherichia,Bacillus, Kloeckera, Saccharmyces.

This broad spectrum of activity against microorganisms is unusual inthat many of the suggested biocides are highly active against a fewmicroorganisms but are completely inactive against all others. Forexample, the applicants inhibitors are advantageous over the recommendedorganic borates, in having a broader spectrum of inhibiting activityagainst many different types of microorganisms, and high activity at lowconcentrations. This combination of high activity at low concentrationsand a broad spectrum of inhibitory activity permits the treatment of thefuels without causing a significant increase in their cost.

Finally the inhibitors of this invention possess good hydrocarbonsolubility coupled with good inhibitory activity. Especially active arethe alkyl esters of the monoand dicarboxynaphthalenes, the formylnaphthoic acid esters, and the 1,8- and 1,2-dialkylnaphthalenes. Thishydrocarbon solubility is especially important in the operational use ofthe inhibitors as turbine engine fuel additives. This operational userequires the control of microorganisms living within the hydrocarbonfuel, sustained by the small amounts of water present. While a watersoluble inhibitor can effectively prevent the growth of microorganismsin the water phase, this effect is wasted if the microorganisms cancontinue to survive in the fuel itself. To effectively prevent thegrowth of the microorganisms in their fuel environment, an inhibitormust be able to enter and disperse in this environment sufficiently longto control their growth. This requires a hydrocarbon soluble inhibitor.Another requirement of a turbine engine fuel additive suitable foroperational use is that the inhibitor must burn freely in the engineWithout leaving corrosive residues or forming corrosive gases. Thislatter requirement eliminates most of the potentially valuableconventional biocides of the prior art. These inhibitors are generallycompounds having halogens or heavy metals in the molecule which uponignition leave corrosive residues or produce corrosive gases. Incontrast the inhibitors of this invention do not contain halogen :orheavy metals and are therefore considered satisfactory for operationalfuel use.

While all of the above compositions inhibit the formation of sludge orslime caused by microorganisms, as in any large group of compounds,there are certain considerations such as substantial differences ofactivity, commercial availability, ease of production, yield,solubility, cost, and the like, which cause some of the compositions tobe favored over the others. Particularly important considerations in thechoice of a particular inhibitory additive for operational use are lowcost of treatment coupled with good activity. Thus, within the disclosedgroup of inhibitors, a smaller group consisting of the 1,8-, 1,6-, andthe three active isomers can be separated from the naphthalene fractionand from each other and used as the individual inhibitors.

However, on the basis of their higher inhibitor activity and goodhydrocarbon solubility, the preferred inhibitor embodiments for turbineengine fuel, gasoline, and fuel oil use, particularly for operationaluse, are the alkylnaphthoates, the dialkylnaphthoates, and thehydroXyalkyl-alkylnaphthoates.

To more fully set forth the detailed workings of this invention, thefollowing illustrative examples of this invention are submitted: 7

EXAMPLE I Determining fungicidal activity of representative compounds ofthis invention against test organisms EXPERIMENTAL The following viabletest fungi are treated as described below:

F usarium oxysporum F usarium roseum Rhizopus nigricans Rhizopusstolonifer Aspergillus niger Alternaria solani One loopful of the aboveviable fungi cultures, spores and mycelia are transferred from agarslants to ml. portions of the nutrient broth given below:

Component: Percentage by wt. Bacto-soytone 1.0 Bacto-dextrose 4.0Deionized water To volume The 80 ml. portion of the fungi and broth areplaced on a sterile trypsinizing flask (300 ml.) and placed on a rotaryshaker for 72 hours at room temperature. At the end of this incubationtime period, 20 m1. of the liquid is homogenized and placed into anothersterile trypsinizing flask (300 ml.) containing ml. of the abovenutrient broth and S00 p.p.m. and 1000 p.p.m. respectively of theinhibitor being tested. The flasks-are placed on a rotary shakeroperating at 240 r.p.m. at room temperature for three days. After thissecond incubation time the flasks are taken off and examined for visiblefungal growth. Untreated controls are used as the basis of comparison.

RESULTS The following chemicals gave substantially complete inhibitionof fungi growth at 500 p.p.m. to 1000 p.p.m.:

1,2-dimethylnaphthalene 1,2-diethylnaphthalene 1,8-dimethylnaphthalene 1,8-diethylnaphthalene 1,6-dimethylnaphthalene 1,6-diethylnaphthalene6-methyl-Z-hydroxymethylnaphthalene 6-propyl-2-ethylnaphthoate1,8-dimethylnaphthoate 1,2-diethylnaphthoate2,6-dihydroxymethylnaphthalene 1,6-dipropylnaphthoate6-formyl-2-methylnaphthoate 6-formyl-2-hydroxymethylnaphthalene8-formyl-1-hydroxymethylnaphthalene EXAMPLE II A 100 ml. portion of fueldesignated by the A.S.T.M. as I.P.4 fuel is layered over 10 m1. ofmineral salt medium in 250 ml. Boston Round Bottles. Sufiicient testcompound is added (none is added for the control) to give concentrationsof 500 and 1000 ppm. in the water phase.

EXPERIMENTAL +-luxuriant growth, no control +++-substantial growth, noeffective control ++-moderate growth, a little control +-little growth,fairly good control None-no growth, complete control TABLE IConcentration in p.p.m. and Control Obtained Chemical Tested 500 ppm:1,000 ppm.

1,2-dimethylnaphthalene 1,2-diethylnaphthaleue 1,8-dimethylnaphthaleneLs-diethylnaplithalene 1,6-dimethyh1aphthalene 1,6-diethylnaphthaleneG-methyl-Z-hydroxymethylnaphthalene- 40 fi-propyl-Q-ethylnaphthoate1,8{1imethylnaphthoate I 1,2-diethy1napht-hoate2,6-dihydroxymethylnaphthalene 4- None.

1,6-dipropylnaphthoate fi-l'ormyl-Q-methylnaphthoate None.

6-l'ormy1-2-hydroxymethylnaphthalene.- None.8-formy1-2-hydroxymethylnaphthalene We claim:

1. A hydrocarbon distillate aviation jet fuel composition comprising amajor amount of an essentially aro- 6O matic-free hydrocarbon distillatefuel to which has been added a minor amount of a disubstitutednaphthalene of the structure sedimentation.

2. A method of protecting airplane fuel tanks and fuel filter systemsfrom clogging and corrosion caused by microbiological growth in saidfuel tanks and said fuel filter systems which comprises contacting saidfuel tanks and said fuel filter systems with a hydrocarbon distillateaviation jet fuel composition comprising a major portion of anessentially aromatic-free hydrocarbon distillate aviation jet fuel towhich has been added a minor amount of a disubstituted naphthalene ofthe structure wherein R and R are substituent groups having from 1 to 6carbon atoms which substituents are selected from the group consistingof alkyl, hydroxyalkyl, formyl, and the alkyl esters of carboxy, saiddisubstituted naphthalene being present in sufiicient concentration toinhibit the formation of microbiologically induced sludge, slime, andsedimentation.

3. The composition of claim 1 wherein the di-substituted naphthalene isa mixture of 1,8-dialkyl, 1,2-dialkyl and 1,6-dialkylnaphthalenes.

4. The composition of claim 1 wherein the di-substituted naphthalene is1,8-dimethylnaphthalene.

5. The composition of claim 1 wherein the di-substituted naphthalene is1,2-dimethylnaphthalene.

6. The composition of claim 1 wherein the di-substituted naphthalene is1,6-dimethylnaphthalene.

7. The composition of claim 1 wherein the di-substituted naphthalene isfi-hydroxyalkyl-Z-alkylnaphthoate.

8. The composition of claim 1 wherein the disubstituted naphthalene is1,8-dialky1naphthoate.

9. The composition of claim 1 wherein the di-substituted naphthalene is1,2-dialkylnaphthoate.

10. The composition of claim 1 wherein the di-substituted naphthalene is1,6-dialkylnaphthoate.

11. The method of claim 2 wherein the disubstituted naphthalene is amixture of 1,8-dialkyl, 1,2-dialkyl, and 1,6-dialkylnaphthalenes.

12. The method of claim 2 wherein naphthalene is1,8-dimethylnaphthalene.

13. The method of claim 2 wherein naphthalene is1,2-dimethylnaphthalene.

14. The method of claim 2 wherein naphthalene is1,6-dimethylnaphthalene.

15. The method of claim 2 wherein the disubstituted naphthalene is6-hydroxyalkyl-2-alkylnaphth0ate.

16. The method of claim 2 wherein the disubstituted naphthalene is1,8-dialkylnaphthoate.

17. The method of claim 2 wherein the disubstituted naphthalene is1,2-dialkylnaphthoate.

18. The method of claim 2 wherein the disubstituted naphthalene is1,6-dialkylnaphthoate.

the disubstituted the disubstituted the disubstituted References CitedUNITED STATES PATENTS 1,814,745 7/1931 Elliott 44-80 X 2,680,058 6/1954Harris et al 44-76 X 2,918,360 12/1959 Lauer 44--70 X 2,975,042 3/1961Summers 44-56 2,975,043 3/ 1961 Ambrose 44-72 3,206,398 9/1965 Marloweet al 252-8.55 3,223,621 12/1965 Marlowe et al 2528.55

OTHER REFERENCES Sachanen The Chemical Constituents of PetroleumReinhold Publishing Corporation, 1945, p. 200.

Gregory, Uses and Application of Chemical and Related Materials-ReinholdPub. Corp, June 1939, p. 400.

DANIEL E. WYMAN, Primary Examiner.

M. WEINBLATT, Y. M. H. SMITH,

Assistant Examiners.

1. A HYDROCARBON DISTILLATE AVIATION JET FUEL COMPOSITION COMPRISING AMAJOR AMOUNT OF AN ESSENTIALLY AROMATICFREE HYDROCARBON DISTILLATE FUELTO WHICH HAS BEEN ADDED A MINOR AMOUNT OF A DISUBSTITUTED NAPHTHALENE OFTHE STRUCTURE